The subject matter disclosed herein relates to a mechanism for a circuit breaker. In particular, the subject matter disclosed herein relates to a mechanism coupled to the circuit breaker that opens a contact arm structure and discharges the stored energy the mechanism springs prior to the circuit breaker being installed or removed from service.
Air circuit breakers are commonly used in electrical distribution systems. A typical air circuit breaker comprises an assembly of components for connecting an electrical power source to a consumer of electrical power called a load. The electric circuit the circuit breaker is connected to is referred to herein as the protected electric circuit. The components are referred to as a main contact assembly. In this assembly, a main contact is typically either opened, interrupting a path for power to travel from the source to the load, or closed, providing a path for power to travel from the source to the load. In a particular type of circuit breaker, referred to as an air circuit breaker, the force necessary to open or close the main contact assembly is provided by an arrangement of compression springs. When the compression springs discharge, they exert a force that provides the energy needed to open or close the main contacts. Compression springs that provide a force to close the main contacts are often called closing springs. Compression springs that provide a force to open the main contacts are often referred to as contact springs.
The air circuit breakers may be installed in several different configurations. The simplest method is typically referred to as a “fixed breaker” where the installer mounts the air circuit breaker and utilizes hardware, such as bolts for example, to couple the air circuit breaker to the source and load electrical conduits. In this instance, when maintenance or repair is required, the hardware coupling the breaker must be removed before the maintenance or repairs can be performed.
Alternatively, the air circuit breaker may be mounted within a mechanism referred to as a drawout. A drawout is a device well known in the art that holds and carries the air circuit breaker into and out of contact with electrical connections for the source and load. To remove the air circuit breaker from service, the drawout automatically disconnects the circuit breaker from the electrical circuit and moves it into a position for servicing.
In the drawout installation, it is desirable to disconnect the circuit breaker from the protected electrical circuit and to discharge the energy in the compression springs prior to initiating the service work. Issues sometimes arise when retrofitting an older drawout unit with a newer model circuit breaker since interlocks mounted in the drawout unit to discharge the compression springs may not be compatible with the new circuit breaker.
While existing circuit breakers are suitable for their intended purposes, there still remains a need for improvements particularly regarding the operation of the circuit breaker and the discharging of the circuit breaker compression springs to allow the servicing of the circuit breaker in a variety of applications.